TORONTO -- Ontario's Liberal government is delaying the sale of its largest electricity transmission utility because it will hurt federal Liberals campaigning for the Oct. 19 election, the provincial NDP charged Monday.

The Progressive Conservatives and New Democrats oppose the sale of Hydro One, and both warned the government that public opinion surveys show the vast majority of Ontario voters are against it as well.

"One of the things they've decided to do is delay the release of the (Hydro One) prospectus to protect Justin Trudeau from any negative outcomes that the revealing would perhaps cause," said NDP Leader Andrea Horwath. "This is something Ontarians know is the wrong decision that the Liberals are making, and it will hurt Justin Trudeau on the campaign trail."

The opposition parties warn the Hydro One sale will lead to even higher electricity prices in a province which already has some of the highest rates in Canada.

"Thousands of Ontarians firmly believe that this proposal will raise hydro rates, making life more and more unaffordable," said PC Leader Patrick Brown, who took the oath of office as the new MPP for Simcoe North Monday after winning a byelection Sept. 3.

Brown started his first question period as Official Opposition leader asking the Liberals to "hit the pause button" on the Hydro One sale.

"Families are concerned that energy prices are out of whack in Ontario, and the fire sale of Hydro One is only going to make that worse," he said. "This is what I've heard the most about around Ontario in the past year, and it's absolutely why I wanted to ask it as my first question at Queen's Park."

Finance Minister Charles Sousa declined to answer questions about the timing of the Hydro One sale, but rejected claims it was delayed to protect the federal Liberals from negative fallout during the election campaign.

"I'm not going to comment on the date (for a prospectus) but I can tell you with confidence that we're moving forward as we anticipated," said Sousa. "Everything is on track."

The Liberals hope to raise $9 billion from a 60 per cent sale of Hydro One, and plan to put $4 billion into infrastructure projects while the rest would be used to pay down hydro debt.

Premier Kathleen Wynne said the government needs the money from the sale to help pay for its $130-billion, 10-year program for public transit and infrastructure projects.

"Why is this a hill to die on? Because investing is a hill to die on," said Wynne. "We know that this kind of investment is absolutely necessary across the province, so that's why this is a fundamental of our platform."

Brown should explain why he is opposed to selling provincial assets when he has spoken in favour of privatization in the past, added Wynne.

"Now he's inconsistently arguing that's not a good thing to do," she said.

Horwath wasn't convinced Brown and his Conservatives were the NDP's allies in opposing the Hydro One sale.

"We haven't seen much of Patrick Brown, but we do know the history of the Conservative party, and they are all in favour of privatization in our electricity system," said Horwath. "They may not like the way the Liberals are doing it, but make no mistake, if the Conservatives were in power they would be doing the same thing, maybe a little differently."

CUPE Ontario president Fred Hahn was outside the legislature as MPPs returned from the summer break Monday, handing out cards stating that Hydro One should be kept in public hands.